Water heater



FIG. 1 is a perspective view of a water heater showing our new design;

FIG. 2 is front elevational view thereof;

FIG. 3 is rear elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom view thereof. 

The ornamental design for a water heater, as shown and described. 